2-Chloro-2-deoxyadenosine (2-CDA) is an adenosine deaminase-resistant congener drug with potent activity in chronic lymphoid malignancies. 2-CDA is also selectively toxic to normal lymphocytes and monocytes, and is currently under study in various autoimmune disorders. Under investigator-sponsored IND #39,111 researchers have initiated preliminary phase I/II open-label trials of 2-CDA in patients with severe, refractory rheumatoid arthritis (RA). Objective responses observed in some patients in the phase I/II trials justify increasing patient...